The C-G can be installed in factory TMCC locomotives or TMCC upgraded locomotives. This is a microprocessor based design that allows for software updates to accommodate functional changes and possible future enhancements. The C-G is mounted on the motor and reads a tach tape on the flywheel to measure relative distance and determine relative speed. An optional output for ground light control is provided; the ground lights will be extinguished at approximately 10 MPH and lit at other times. The MPH calculation is based on an average gear ratio and driver diameter and may vary between models. The C-G is fabricated on a printed circuit board with the dimensions of 1.3" x 0.4" in size. The overall height including components is approximately 0.125".